The invention refers to a device for transferring a rotational motion into a longitudinal movement or vice versa and being of the type defined in the preamble of the accompanying claim 1.
Devices of this kind are useful, e.g. as control members and as transport devices. A known device is shown in the U.S. Pat. No. 3,903,748. In this device the axes of the rolling bodies are arranged in parallel with the central cylindrical shaft. As the rolling bodies move along a helical line about the shaft it is therefore inevitable that a certain sliding must appear at the contact between the shaft and the rolling bodies, which results in friction losses and wear as the rolling bodies must be subjected to constrained guiding in their track through contact with a ramp with a surface formed as a helical line.
The purpose of the present invention is to provide a device of the above mentioned type, in which the friction losses and wear caused by the above mentioned reasons are eliminated and in which comparatively large forces can be transferred as the rolling bodies can be biased with large force between the shaft and the sleeve and can be safely and accurately guided in a cage.
This is according to the invention obtained by a device having the characteristics defined in the accompanying claim 1.